The present invention relates to a drive assembly for presses used for extracting cocoa butter from a cocoa paste.
As is known, cocoa butter is conventionally extracted from cocoa paste, to make chocholate and cosmetic and pharmaceutical products by using press filters which are driven by hydraulic pumps.
Also known is the fact that conventional drive assemblies used for the above mentioned application comprise a low-pressure pump, held in a housing, and a high pressure pump, having three low speed pistons which are driven by a flywheel, crank shaft and pistons.
More specifically the two pumps are started together, in a tandem relationship, and are controlled by a pressure gauge, including a suitable electrical contact adapted to cause the low pressure pump to be stopped at a given pressure, usually 300 bars, whereas the high pressure pump operates from 300 bars upward.
Then, a conventional valve driving means disengages a piston of the mentioned high pressure pump, as a pressure of 420 bars is reached, and another valve driving means disengages a second piston at 450 bars.
The third piston, on the other hand, continues to operate up to the end of the pressing cycle, that is up to a pressure of 500 bars, which usually corresponds to a pressing end pressure.
Then, the two pumps convey the cocoa oil to discharging cylinders, with a consequent decrease of the pressure in the extracting chambers, adapted to allow the cakes or cocoa panels to be discharged.
While the above disclosed operating cycle has been structurally improved, it has some drawbacks which are substantially due to the use of a low-pressure pump.
The latter usually consists of a conventional radial-piston pump the pistons of which pump with a variable pressure, the pressure variation being obtained by preset commands, for example from 3 to 5 commands.
To this pump there is conventionally applied a joint on the head portion of which there is mounted a small reducing unit to which there are sent 5 preset pulses indicative of corresponding speed revolutions and, accordingly, of corresponding pump flow rate values.
In this connection it should be pointed out that in this low pressure pump the hydraulic oil is never replaced and, accordingly, the expected life of this pump is of 2 or 3 years.
Moreover, as such a pump fails, it can not be immediately replaced since the user has not available in his store such a pump the type of which, moreover, is modified each 6 or 7 years by the manufacturers.
Thus, as such a pump fails, it must be fully replaced.
The high pressure pump, on the other hand, does not present the disclosed problems since it exclusively requires a periodic replacement of the piston seals.
This seal replacement operation, however, requires a previous disassembling of all of the piston rods and related piston guiding elements, which represents a comparatively complex operation.